Raman Spectroscopy of Carbon Nanotubes under Axial Strain

Resonant Raman spectroscopy of individual carbonnanotube bundles under axial strains up to 17% arepresented. This strain causes nanotube debundlingwhich gives insight into the nature of the broadmetallic G- band. For metallic nanotubes, the G- bandupshifts and narrows with strain, making it appearmore semiconductor-like. This metal to semiconductortransition is irreversible with strain, indicatingthat nanotube-nanotube coupling plays a significantrole in the observed G- band of metallic nanotubes.The vibrational andelectronic properties of these nanotubes under strainare modeled using tight-bindingcalculations.A systematic study of surface enhanced Ramanspectroscopy (SERS) of carbon nanotubes. Ramanspectra of individual carbon nanotubes are measuredbefore and after depositing silver nanoparticles.Regions exhibiting SERS enhancement were locatedrelative to a grid, allowing subsequent scanningelectron microscopy to be performed. SERS enhancementfactors up to 134,000, a consistent upshift in the Gband Raman frequency and nanoparticle heating inexcess of 600°C are revealed.